Bowling balls are generally manufactured such that the ball is slightly denser adjacent the top of the ball, so that when finger holes are custom fitted into the top of the ball, proper balance about the various axis of the ball is achieved. Various finger holes require the removal of different amounts of mass; and accordingly, the resultant weight of one ball for one particular bowler will differ from the resultant weight of the same ball for a different bowler because of the difference in the masses removed from the top of the ball during the formation of the finger holes.
The finger holes of a bowling ball must therefore be placed in superimposed relationship respective to the area in which the underlying top weight is located. The finger holes usually extend into the top weight and the top weight must be of a density which partially compensates for the removal of material therefrom. However, within a particular geometrical area which describes the underlying top weight, it is customary to indiscriminately place the finger holes into the ball with no regard to the direction within which the ball is to be thrown or rolled. Hence, in custom fitting one's hand to a bowling ball, no one heretofore has considered the dynamic properties of the ball. For example, it is quite possible for one to select two identical bowling balls, form the finger holes in properly indexed relationship respective to the top weight, and yet end up with the finger holes arranged a substantial amount out of phase with one another, so far as regards the dynamic stability of the ball.
Many skilled in the art of bowling balls consider that a perfect bowling ball is one which is perfectly balanced, that the material removed during formation of the finger holes is precisely superimposed in the precise geometrical center of a symmetrical body of denser material, and that the surface of the bowling ball should be absolutely spherical. In actual practice, such a bowling ball is achieved through accident rather than design for the reason that the finger holes seldom are placed as one envisions, nor is the distribution of mass within the ball absolutely perfect. Accordingly, it is almost impossible for one to drill finger holes within two identical bowling balls and for the bowling balls to subsequently perform identically respective to one another, although the same expert player may be rolling the balls.
Therefore, when a bowler finds a suitable ball with which he can consistently roll a high score, it is catastrophic when, for one reason or another, he must abandon his old bowling ball in favor of a new ball.
It would therefore be advantageous if one could provide a bowling ball whose dynamic stability characteristics are such that the ball would travel down the bowling lane in an improved and reproduceable manner, and upon striking the pins, the ball would continue to travel in the same direction, so that once the bowler learns to roll the ball in such a manner that he can obtain a strike, he could thereafter have other balls drilled in accordance with the present invention and always expect the other balls to react in the same identical manner. Such an expedient is the subject of the present invention.
Bowling balls often must be of a specific weight and size, or lie within a certain specified range of weights and sizes, in order to compete in national competition. Moreover, the material of construction, as well as the weight distribution of the mass of the ball, must comply with the specifications formulated by the National Bowling League.